The subject matter disclosed herein relates to industrial processes, process facilities, and device diagnostics, with particular discussion below that concerns the quality of gasses that these facilities use to operate certain devices (e.g., control valves) found on the process line.
Industrial process facilities that operate processes may utilize many varieties of flow controls that regulate a flow of process fluids (e.g., gas and liquid). Problems with these devices can often disrupt the process. These disruptions can lower yields and reduce quality. Also, in large refineries, chemical plants, and power plants, technicians may need to troubleshoot and repair the problematic devices. The service on the devices can lead to significant expense from process downtime and other collateral issues.
Devices for use as the flow controls include valve assemblies that operate under the influence of an operating fluid, namely, compressed or pressurized gas (“instrument gas”). Often, the facility includes a fluid delivery system with a source (e.g., a compressor) and lines (e.g., tubing) that plumb the valve assemblies to the compressor. This fluid delivery system delivers the instrument gas under pressure to the valve assembly. In conventional configurations, the valve assembly has a pneumatic actuator, which utilizes the instrument gas to change the position of a plug relative to a seat, thereby modulating the flow of the process fluid through the valve assembly. The valve assembly can also incorporate electrical and/or electro-pneumatic components to regulate the flow of the instrument gas into the pneumatic actuator.
Some of the components in the valve assembly, including the electrical and electro-pneumatic components, are sensitive to characteristics of the instrument gas. These characteristics include, for example, levels of contaminants, relative humidity, temperature, and the like. Specifications for the valve assembly may set out appropriate levels and/or operating ranges for the characteristics of the instrument gas. These levels define the “quality” of the instrument gas that may help maintain the operation of the valve assembly. Deviation of the characteristics from these levels, however, may expose the sensitive components in the valve assembly to instrument gas that can degrade performance and, eventually, can lead to problematic operation of the valve assembly that requires repair and/or replacement of the valve altogether.
The fluid-delivery system may employ safeguards to maintain the characteristics of the instrument gas at or near the levels set out for operation of the valve assembly. The safeguards may include, for example, conditioning devices (e.g., filters, scrubbers, humidifiers, de-humidifiers, heaters, chillers, etc.). These devices condition the instrument gas to meet the specifications for use by the valve assemblies.
In many conventional applications, the conditioning devices reside at locations remote, and often far removed, from the valve assemblies that receive the instrument gas. These locations afford the fluid delivery system with little in the way to protect against changes in the characteristics that may occur downstream of the conditioning devices. For example, particulates and other contaminants (e.g., lubricants and oils) may enter the lines that transfer the instrument gas between the conditioning device and the valve assembly. Moreover, maintenance and/or other system-level services on the fluid delivery systems can introduce moisture that changes the relative humidity of the instrument gas that enters the valve assembly.
This moisture, and other contaminants, can transit through the fluid delivery system to the components of the valve assembly. Unfortunately, conventional arrangements of fluid delivery systems often lacks appropriate feedback downstream of the conditioning devices to detect changes in the characteristics of the instrument gas. This oversight does not allow facility operators to appreciate, for example, particle accretion into the instrument gas downstream of filters, let alone to provide data that reflects the characteristics of the instrument gas found locally at and/or near the valve assemblies on the process line.